WO 00/00072 discloses interfolded napkins comprising first and second napkin sheets. The first napkin sheet is divided into many napkins connected to one another by tab parts of a line of perforation. The second napkin sheet is similarly formed. The first and second napkin sheets are interfolded with each other to form a stack of interfolded napkins. The lines of perforation of the first sheet may be aligned with folds of the second sheet so that the first sheet is folded at the lines of perforation in the interfolded stack. In an alternative stack disclosed in WO 00/00072, the interfolding is such that the lines of perforation are positioned between adjacent folds so that folds are not formed at lines of perforation. In both versions, the first and second sheets can be described as being interfolded with each other in an offset way since the lines of perforation of the first and second sheets are offset with respect to one another along the longitudinal direction of the first and second sheets.
In WO 00/00072, napkins of the stack are dispensed from a dispenser through a dispenser opening and torn away from the corresponding napkin sheet at the lines of perforation. The longitudinal offset of the lines of perforations of the first sheet relative to the lines of perforations of the second sheet result in the dispenser revealing just one more forwardly protruding sheet at the dispensing opening to reduce the chance of both sheets being grasped as would occur if the offset was marginal or non-existent. The interfolding of the sheets means that when a napkin of the first sheet is pulled through the opening of the dispenser, part of a napkin of the second sheet comes through the opening with it. The protruding part of the napkin of the second sheet can be grasped by a user for dispensing convenience. As compared to interfolded napkins where each napkin is pre-separated from one another in the stack (in contrast to interfolded offset sheets where each napkin is connected to an adjacent napkin by a line of perforation), there is a reduced risk for a dispensing failure to occur whereby the next napkin in the stack is not pulled through with the napkin being dispensed.
U.S. Pat. No. 1,381,307 and EP 0287766 also disclose stacks of interfolded offset sheets.
The prior art interfolded sheet stacks enable a first sheet hygiene product (e.g. napkin, towel, tissue or the like) of one sheet to be pulled partly through a dispensing opening of a dispenser when a second sheet hygiene product of the second sheet is dispensed through the dispensing opening for convenience in revealing to a user the next product to be dispensed. While the prior art interfolded stacks are generally successful in pulling a product of the other sheet with the product of the other sheet being dispensed for most of the stack, the present inventors have found that a dispensing failure can still occur at the transition from one stack to a next stack in the dispenser.